Iterating over ctypes pointer causes hang or segmentation fault

Trying to create iterable (list, tuple, set etc.) from PyCPointer instance leads to hang or segmentation fault.
This code causes hang and memory leak which goes until oom-killer kills python process:

import ctypes
x = ctypes.c_int32(12345)
buf4_p_t = ctypes.POINTER(ctypes.ARRAY(ctypes.c_byte, 4))
buf_p = ctypes.cast(ctypes.byref(x), buf4_p_t)
list(buf_p)

Similar code that causes segmentation fault:

import ctypes
x = ctypes.c_int32(54321)
xp = ctypes.pointer(x)
list(xp)

Iterating over pointer using for statement leads to an infinite loop:
for i in buf_p: print(i)
for i in xp: print(i)
list(for i in buf_p)

Tried on 3.10.3 and 3.11.0a6+, fails at both.

The possible reason is that PyCPointer_Type defines sq_item without defining tp_iter.
Despite I can't imagine any reason why anyone might need to use pointer as iterable/sequence, raising TypeError in such situation would be a better option.

Linked PRs

• gh-126318
• gh-157801

Start with the ctypes PyCPointer behavior shown in the two reproductions and confirm the hang, memory growth, and segmentation fault on the affected Python versions. Trace how pointer indexing and iteration interact, then verify that the completed behavior safely rejects iteration without hanging or crashing; linked PRs gh-126318 and gh-157801 provide existing work to inspect.